The only other recent forward Toronto has selected in the first round was Jiri Tlusty in 2006 and the jury is still out on him, (although they won't be out for long). Before that. the last first round picks spent on a forward position was when they selected the following;
Alex Steen, 24th overall in 2002. Spent three full seasons in Sweden after being drafted and wasn't a full-time NHLer until age of 21. He of course was traded away...for Lee Stempniak...along WITH Carlo Colaiacovo.
Brad Boyes, 24th overall in 2000. He played 238 games in the AHL before becoming an NHL regular as a 23 year old, in St. Louis.
Luca Cereda, 24th overall in 1999. Played 161 AHL games, never made the big time.
Nik Antropov, 10th overall in 1998. Would play one full season in Russia after being drafted and played a half year in the AHL along with two and a half unproductive years in the NHL. Didn't contribute regularly unil he was 22.
Landon Wilson, 19th in 1993. Played two more years of college after the draft as well as a full season in the AHL before being traded away.
Brandon Convery, 8th in 1992. He toiled in the "A" for 243 games and never really amounted to much in the NHL.
Grant Marshall, 23rd in 1992. Spent one year in each of the AHL and IHL and was lost to Dallas as free agent compensation....for signing Mike Craig.
Scott Thornton, 3rd in 1989. Played 114 AHL games before being traded away and not becoming a regular til age 23.
Rob Pearson, 12th in 1989. Would play only 30 AHL matches. In his first full season he became one of only 10 players to have at least 20 goals and 200 PIMS in a season which they were 21 or younger. Interestingly, of the ten one was a defenseman, Scott Stevens and four of them were Maple Leafs. Along with Pearson, Wendel Clark did it in both of his first two seasons, Rick Vaive once and Tiger Williams once. Unfortunately for Rob Pearson (and the Leafs), that was his pinnacle.
Scott Pearson, 6th in 1988. Played parts of three AHL seasons before barely becoming a regular as a 23 year old with Quebec when he scored 13 goals and 1 assist. He was the first player in almost 70 years to have that many goals with one or zero helpers, also the last to it since.
From 1983 to 1986 the Leafs actally would do well selecting forwards in the first round and it showed in the fact that none of the three players played even one game in the minors.
Vincent Damphousse, 6th in 1986.
Wendel Clark, 1st in 1985.
Russ Courtnall, 7th in 1983.
These three would go on to play exactly 3200 NHL games and a collectve 21 seasons in Toronto. The first rounder they took among these three in 1984, defenseman Al Iafrate also played almost 800 NHL games. So from '83 to '86 their first round picks were terrific, and still the losing continued.
In summary most individuals except the very top tier player, require seasoning in the minor leagues. This isn't to say that Kadri will not be a top player, we can't be sure yet. History says we will find out in the next few years though.